Heat 2 tablespoons of oil in a frying pan. Fry the slices of bread in it from both sides until light brown, season with salt and remove. Wash, clean, quarter and seed the tomatoes. Cut the fruit flesh into small cubes.
Wash parsley, shake dry and, except for something to garnish, pluck leaves from the stalks and chop them. Mix tomato cubes, 1 tablespoon of oil and parsley, season with a little salt. Wash the mussel flesh and dab dry.
Heat 1 tablespoon of oil in a frying pan. Fry the mussel meat for 1-2 minutes on both sides, season with salt and pepper and remove. Grate cheese. Put slices of bread on a baking tray, place some tomato mixture on each and 2 scallops on each.
Sprinkle cheese over it and bake under the preheated grill of the oven for 3-4 minutes until the cheese has melted. Remove bread, arrange on plates and garnish with parsley.